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Presentation on theme: "Fossils and the Rock Record"— Presentation transcript:

2 Geologic History PrinciplesLaw of Uniform ProcessesLaw of SuperpositionLaw of Cross-cutting RelationshipsLaw of Included Fragments

3 Law of Uniform ProcessesThe processes which are changing the earth’s surface today are the same processes which acted in the past

4 Law ofSuperpositionThe oldest rock layer is on the bottom of an undisturbed rock column, and each higher layer is younger

5 Law of Cross-cutting RelationshipsA fault or intrusion is younger than the rock layers it cuts through

6 Law of Included FragmentsPieces of one rock found in another rock must be older than the rock in which they are found

7 Tree Rings This tree was approximately how old? About 17 yearsHow did you determine this age?By counting the number or light (summer) and dark (winter) rings

8 Geologic Time ScaleWhich represents the longest time interval – era, eon, or epoch?Which of the three eras represents the longest amount of time?Approximately how old is the earth?eonpaleozoic4.6 billion years

9 ABCDEFGXHIJKLYRelative Age: List the following rock layer in chronological order starting with the oldest layer.

10 Relative AgeIn the previous slide you know rock layer Y is younger than rock layer C because _________________________________.In the previous slide you know rock layer H is older than rock layer I because _________________________________.In the previous slide you know rock layer X is younger than rock layers D, E, and F because _________________________________.Y cuts across CH is under ID, E, and F are included in X

11 ____________ Age: By measuring the percentages of parent and daughter isotopes in some rocks or fossils, an age in years of that object can be determined.Absolute

12 FossilsPicture C shows what two types of fossils, and how do they form?Picture D shows what type of fossil?Picture B shows what type of fossil?Mold-organism decaysCast-mold fills with mineralsTrace fossilActual remains